New Insights into the Mechanism of JNK1 Inhibition by Glutathione Transferase P1-1
New Insights into the Mechanism of JNK1 Inhibition by Glutathione Transferase P1-1
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DOI：
10.1021/bi300559m
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发表时间：
2012-09-18
期刊：
影响因子：
2.9
通讯作者：
Caccuri, Anna Maria
中科院分区：
文献类型：
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作者：
De Luca, Anastasia;Federici, Luca;Caccuri, Anna Maria
谷胱甘肽转移酶P1-1 （GSTP1-1）在调节c-Jun n -末端激酶（JNK）途径中的作用已被广泛研究，使用已知的JNK亚型在细胞中发挥相反的作用。我们已经表达了JNK1 α 2的异构体，据报道，它可以传递促凋亡信号，我们分析了GSTP1-1存在时该激酶的磷酸化水平和活性。与之前的研究结果相反，我们发现即使在没有底物的情况下，GSTP1-1也能够与未磷酸化且无活性的JNK1 α 2异构体形成复合物。我们还分析了这种相互作用对两种酶活性的影响。该复合物强烈降低了JNK1 α 2的激活程度，并保护了GSTP1-1免于失活。出乎意料的是，谷胱甘肽（GSH）对GSTP1-1对JNK1 α 2的亲和力产生了负面影响，这表明这种硫醇的细胞内水平可能允许对MAPK信号通路进行微调。此外，我们发现GSH与强GSTP1-1抑制剂NBDHEX形成的加合物消除了GSTP1-1与JNK1 α 2之间的相互作用。这些数据在分子水平上证实并扩展了先前在肿瘤细胞系中获得的证据。
The role played by glutathione transferase P1-1 (GSTP1-1) in modulating the c-Jun N-terminal kinase (JNK) pathway has been extensively investigated using JNK isoforms known to exert opposite effects in the cells. We have expressed isoform JNK1 alpha 2, which has been reported to transmit a pro-apoptotic signal, and we have analyzed both the phosphorylation level and the activity of this kinase in the presence of GSTP1-1. Contrary to what previous studies suggest, we found that GSTP1-1 is able to form a complex with the unphosphorylated and inactive JNK1 alpha 2 isoform, even in the absence of the substrate. We also analyzed the consequences of this interaction on the activity of both enzymes. The complex strongly reduced the extent of activation of JNK1 alpha 2 and preserved GSTP1-1 from inactivation. Unexpectedly, glutathione (GSH) exerted a negative effect on the affinity of GSTP1-1 for JNK1 alpha 2, suggesting that the intracellular levels of this thiol may allow a fine-tuning of the MAPK signaling pathway. Moreover, we found that the adduct formed by GSH and the strong GSTP1-1 inhibitor NBDHEX abolishes the interaction between GSTP1-1 and JNK1 alpha 2. These data confirm and extend at the molecular level previous evidence obtained in tumor cell lines.